Various hydraulic powders are produced by pulverizing hydraulic compounds such as Portland cement clinker and blast furnace slag. For example, Portland cement is produced by preparing clinker by burning raw materials such as limestone, clay, iron slag, adding an adequate amount of gypsum to the clinker, and pulverizing the mixture. In the production, to increase a pulverization efficiency, grinding aids such as diethylene glycol and triethanolamine are used. In pulverization, a hydraulic compound is desirably pulverized into a desired particle size as efficient as possible. Thus, grinding aids conventionally have been used in pulverization.
Examples of the grinding aid include oligomers of lower alkylene glycols such as propylene glycol and diethylene glycol, alkanolamines such as triethanolamine, fatty acids such as stearic acid, aromatic compounds such as phenol, hydroxyalkylhydrazine, and t-butylacetic acid. Those have also been known, including use of glycerol as a grinding aid (see, for example, JP-A 11-60298), combination use of lignosulfonate and glycerol (see, for example, JP-A 57-100952), and use of an organic factory waste liquid containing a polyhydric alcohol (see, for example, JP-A 2005-89287). In particular, diethylene glycol and triethanolamine are said to have good pulverization efficiency and be capable of pulverizing into a desired particle size at a relatively fast rate.